WSN Simulation Template for OMNeT++ Stefan Dulman [email protected].

WSN Simulation Templatefor OMNeT++

Stefan [email protected]

energy efficient sensor networks

Presentation Overview

OMNeT++ Introduction

Sensor Network Template

Implementation Example

Discussion and future work

energy efficient sensor networks

OMNeT++ Introduction

energy efficient sensor networks

OMNeT++ Features

Simulator designed for fixed, wired, distributed systems (such as: computer networks, multiprocessor systems…)

Discrete time simulator

It is compatible with: DOS, UNIX, WINDOWS (uses C++ and Tcl/Tk)

Several graphical interfaces allows easy debugging and variables inspection

Offers support for parallel execution

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OMNeT++ Features (2)

Simulated objects are represented by modulesModules can be simple or composed (depth of module nesting is not limited)Modules communicate by messages (sent directly or via gates)One module description consists of:

Interface description (.NED file)Behavior description (C++ class)

Modules, gates and links can be created:Statically - at the beginning of the simulation (NED file)Dynamically – during the simulation

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OMNeT++ Features (3)

Support is offered for:Recording data vectors and scalars in output files

Random numbers (also from several distributions) with different starting seeds

Tracing and debugging aids (displaying info about the module’s activity, snapshots, breakpoints)

Simulations are easy to configure using .ini file

Batch execution of the same simulation for different parameters is also included

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OMNeT++ Features (4)

What is missing or not working as wanted:Mobile entities and wireless communication between them are not includedStatic data types not allowed

For storing data needed by all the modules a central manager has to be createdCommunication with this entity goes by messages (slow!)Using pointers to it is not always good idea (parallel execution)

Execution goes very slow with the increase of the number of messages and when using parametersVery slow 2D graphical interface made in Tk

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Sensor Network Template

energy efficient sensor networks

Template Description

What is it:A fully working project consisting of a network of mobile nodes that can communicate by wireless means. The user has only to implement the wanted algorithm, with no concern on how these issues are handled.

All the parameters of the network can be changed without any need of rewriting any code

Offers (a lot of) easy to use macros for accessing the main functionalities

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Template Description (2)

Characteristics:Implements mobility (Random Way Point alg.)Wireless communication

Simulated by dynamically connecting modules within transmission range

Unidirectional linksSignal strength can be varied from within the nodesEnergy management is also includedNodes have failing probabilitiesMap for area failures can be specified and used

Other maps can easily used for obstacles, fading, etc. (implementation is similar)

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Network Architecture

Central ManagerUsed as a central database

Its main function: stores the connectivity map and updates it upon request

It takes care of reading additional configuration files and sending the information

It is hidden from the display, communication with it is done only with sendDirect() function

Sensor nodes

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Sensor Node Architecture

Sensor node architecture:Layer 0

Sensor

Energy manager

Blackboard

Application

Custom network layers

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Mobility Issues

Approaches to describe mobilityEach node reports its position after a certain interval.

Simulation precision depends on this interval.The smallest the interval the longest the simulation time

Each node reports the equation of the curve of its movement

Manager computes the interaction moments and schedules gates connect/disconnect at those momentsFaster execution (almost 4 times in our simulations)More precise simulationGraphical display no longer linked to the simulator precision

Random Way Point model as default

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Energy Management

Implemented using the blackboardConsumed energy and of the current energy

Data can be accessed from anywhere within a sensor node

Estimation of the lifetime of the node (can be improved by using any desired estimation function)

Warnings can be issued when no energy is left (special behaviours can be implemented in the energy manager; e.g. stop certain components when energy goes beyond a treshhold)

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Reliability Issues

Two kinds of failures implementedNode failure probability

Can be specified for each node separately

Available to all the layers inside a node

Can be set to change over the time

Area failure probability The failure zones are specified as rectangles inside a configuration file

Data is available to all the layers

It can be given any interpretation needed. Easy to extend to a set of maps

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Other Features (2)

Support for beacons is added (needed by the localization algorithms)

A certain number of nodes have fixed positionsAny node can find out if it is a beacon or not

Each node can be displayed in several ways (useful for debugging and presentations: to highlight the discovered paths, the clusters, etc.)

3 distinct graphical signs and 10 colors for each oneCan be modified from anywhere inside the nodeModifications are displayed immediately

Simulation precision is no longer related to display update

User can specify the display rate

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Work in progress

Signal sources:Support for fixed and mobile beaconsSupport for areas of interest

Fixing minor bugs and optimizing the codeRather use new derived classes than parametersFinding the best places to place the functionality (manager or layer0)

Trying to create a library of modules

WANTED: 3D graphical display !!!

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Work in Progress (2)

Tcl/Tk script for:Easy configuration of the network

Designing the maps, node initial positions, initial values, etc.

Generation of project files

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Implementation example

energy efficient sensor networks

Discussions

Address where to download the template:http://wwwhome.cs.utwente.nl/~dulman/tools.htm

Email address:[email protected]